Bizarre calculation of MD8A in VERDI

I am trying to verify the maximum daily 8 hour average (MD8A) calculation for a CAMx output file (july 13 2017). My domain does not include buffer cells. I am using VERDI version 2.4.1
When I calculate MD8A directly from the CAMx netcdf output outside of VERDI, I calculate a MD8A that matches the MD8A value from AMET for that same grid cell.
When I calculate MD8A using the “maxiumum_8hour_average” stats feature in VERDI, the result shown is displaced by 1 col, 1 row. I’ve attached this image showing my analysis and comparison to VERDI:

My target monitor is in grid cell [69,78] (verified in ArcGIS). I’ve labeled my target grid cell [69,78] on the VERDI screen grab on the left. The MD8A that I calculate outside of VERDI is on the right - a screen grab from excel. Note that the MD8A calculated in excel from the CAMx netcdf for cell 69,78 matches the MD8A in VERDI for the cell 70,79.

I checked the hourly O3 values in VERDI and in my CAMx netcdf: the hourly O3 values are the exact same for the cell 69,78. Is something strange happening in VERDI when the MD8A calculation occurs? I found this in the VERDI manual, which seems like a straightforward MD8A calculation.
* MAXIMUM_8HOUR_MEAN: Ma (M1, M2, ..., Mn-8) where Mi = mean(var(i,j,k,t(i)), var(i,j,k,t(i)+1), var(i,j,k,t(i+2)), ...,var(i,j,k,t(i+8)), for i = 1..n-8

When I try to probe my domain for the MD8A at cell [1,1] (the southwest corner), VERDI will not produce any results. But if I probe at 2,2 and greater, it will show the MD8A.

Is there a difference occurring due to the consideration of buffer cells, perhaps? My domain does not include buffer cells.
Thanks for your help!

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Hi Lexi,

Thank you for reporting this issue.

Our developers tried reproducing this finding using the CAMx files in our repo. Could you please share the CAMx file you are using?

You can either put it on a google drive, and share the link, or I can find another way for you to transfer it to us.



Here is our file: - Google Drive

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Hi - following up to see if the developers found anything! Thanks

Hi Lexi,

My apologies for the late response. We added a new issue for this on the VERDI github repo, but a solution has not been implemented yet.


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